1. Field of the Invention
The present invention relates to thrust washers and anti-friction spacing elements for vehicle torque converters. In particular, the present invention relates to a two component thrust washer assembly for use in a transmission system of a motor vehicle. A first component is for the wear face and is made of an expensive and extremely durable polyimide material. A second component for engagement with an adjacent portion of the torque converter, is made of a relatively inexpensive material such as a die cast metal.
2. Prior Art
In automotive transmission systems, particularly torque converters, for example, axially aligned components that come in contact with each other usually sustain high impact loading. Also, because of the high loading between components, relatively high wear between components is not unusual. High impact loading on the components and high friction between components in such mechanisms, is inherent in the mechanism because of the job performed by the mechanism. One way to reduce this problem is to change the mechanism but changing one mechanism in a chain is not always practical, since the links in a chain must be able to xe2x80x9ctalkxe2x80x9d to one another. A more practical solution is to develop or redesign individual components in the various parts of the system which will work together and make the system more efficient. In furtherance of such ends certain components in a drive system, for example, have been improved. The 1981 U.S. Pat. No. 4,268,040 to Bainard et al teaches a combination thrust washer and seal that is fabricated from a composite of several materials, integrated into a dual functioning component. The problem solved by the component taught in this patent is overshadowed by a new problem created by the component. Its combination thrust washer and seal is fabricated with a composite of several materials. Constant high impact on the composite of materials has the effect of separating the materials and when separation of materials occurs, failure of the component occurs.
The 1988 U.S. Pat. No. 4,776,237 to Premiski et al teaches thrust washers used on each side of the planet gears of a planetary gear mechanism. Each thrust washer has oil ports that permit the flow of oil through the thrust washer. However, the oil ports are in the body of the thrust washer and remain a constant size. There is no provision to clean out the oil ports, should a blockage occur. Even the relaxation of the components in the planetary gear mechanism will not function to clear a port in the body of the thrust washer. The 1996 U.S. Pat. No. 5,509,738 to Haynes et al teaches a composite journal and thrust bearing system wherein the thrust face of an element and the journal of the bearing housing are lined with material having self-lubricating properties. The Haynes patent essentially teaches that the thrust face of an-element and the surface of a housing may be veneered with a material with self-lubricating properties. In the case of veneered surfaces of the nature proposal, the veneered material is usually applied to the surface with heat. Heat also separates the veneered material from the surface. This presents a problem because heat is usually generated in housings supporting journal and thrust heating systems.
U.S. Pat. No. 5,829,888 to Bharagava et al discloses a metal thrust washer having a first face with oil grooves and an opposed second face with two outwardly projecting members, one used for locating and the other used for securement of the washer in a torque converter.
The present invention is a two component improved thrust washer having self-lubricating anti-rotational, anti-friction and positive lubrication characteristics, with high impact load capability. The invention provides a two component improved thrust washer, the first component being fabricated from solid, unitary material such as polyimide resin integrated with solid, carbon and/or graphite lubricant material. Preferably the first component is fabricated from a material marketed by Du Pont under the trade named VESPEL SP-21D. This first component has a wear face with spaced, open oil grooves on one surface thereof, and anti-rotational pins on an opposite surface. The open oil grooves extend radially across the diameter of the body of the thrust washer and define oil channels when the surface of the thrust washer containing the oil groove is in a close surface-to-surface relationship with the surface of an adjacent component in a torque converter mechanism. The oil channels are self cleaning. During relaxation of the components of the torque converter, the oil channels revert to open oil grooves, which are self cleaning. The polyimide resin material from which the first component of the thrust washer is fabricated is a solid material, having integrated therein a solid lubricant material, such as carbon graphite, which renders the material self-lubricating. Thus the first component of the improved thrust washer is self-lubricating. Although the material from which the first component is fabricated is a composition of several materials, it is fabricated from a unitary, solid material, without veneered surfaces. The polyimide resin material from which the first component is fabricated is expensive and difficult to work, but has very desirable high impact loading characteristics which become characteristics of the first component.
The second component is used to positively engage an adjacent element of the torque converter. It has on its first surface a mating portion for mating with the first component, such as a plurality of openings positioned to receive the above mentioned anti-rotational pins projecting from the first component. The second component also has engagement means for connecting with an adjacent portion of the torque converter in which it is used.